RT-PCR evaluation of viral contamination in five shellfish beds over a 21-month period

Five shellfish beds were sampled for 21 months and evaluated for microbial contamination. Viral extraction was performed on dissected tissues and the clinically most important enteric viruses (hepatitis A virus, small round structured virus, rotavirus and enterovirus) were searched for by RT-PCR and hybridization. Among the 104 samples analysed, 66% were contaminated by at least one virus and 34% were negative for any virus. The two sites regularly contaminated by faecal coliforms had the highest percentage of viral contamination and HAV was detected only in these sites. However, sampling sites meeting the criteria for commercialisation showed occasional viral contamination and viruses were detected in samples with no faecal coliform contamination.